But . . but . . plants and trees still grow in those places where the rainwater is washing pollution out of the air. Look at China and India with their terrible, uncontrolled air pollution. And yet they feed their hungry masses. Their plants must grow using that acid rain. Lightening even releases nitrogen into the rainwater during a thunderstorm, so it can be a mild fertilizer.
You could spend your life and your savings buying distilled water and adding in the minerals that plants want, in tiny trace amounts. Nobody's going to do that. It would be interesting to know if there is an accumulation of lead in plants and trees in the Flint MI area from that toxic water. Plants are pretty good at using what they need and filtering out the rest.
I have three different options for water here at my house. Tap water which tastes pretty good and has a pH of about 7.6, well water that tastes terrible and has a pH of 8.2 or thereabouts, and rain water which is brown and funky but all my edibles, orchids and acid-loving plants get it until it runs out (it takes about 3 weeks of no rain for me to run out of my 1300gal. of rainwater in a hot springtime season). Some plants react with iron chlorosis if I have to irrigate with the well water for too long, but that has only happened once in nearly 9 years. I use a little expensive tap water when that happens, and pray for rain!
You can even water your plants with grey water, if you have a way to collect it. Little amounts of soap, shampoo, detergent etc. don't affect it as far as the plants are concerned. They're surfactants and can even help to wet the soil if it has dried out too much.
For people to drink, tap water is usually safe but for plants rain water is always best even if it is falling through polluted air.
